This invention generally relates to systems and methods for ultrasonic inspection of manufactured articles, and in particular, to methods for ultrasonic inspection of damaged structure underlying non-planar surfaces.
Non-destructive inspection (NDI) of structures involves examining a structure without harming the structure or requiring significant disassembly. Non-destructive inspection is typically preferred to avoid the time and costs associated with the removal of a part for inspection and to avoid the potential for causing damages when inspection is needed. Non-destructive inspection is used in the aircraft industry to inspect aircraft structures such as composite structures and bonded panels. Inspections may identify defects such as cracks, discontinuities, disbonds between layers, voids, and areas having undesirable porosity. Preventive inspections may be performed during manufacturing and at any time during the service life of an aircraft structure to validate the integrity and fitness of the structure. Inspections may also be prompted by incidents such as collisions and ballistic impacts that are suspected or known to cause damages.
Various types of ultrasonic methods are used to perform non-destructive inspections. For example, a structure may be inspected by a pulse-echo method wherein a sensor device sends ultrasonic pulses into a structure and receives echo pulses that reveal the condition of the structure. Data acquired by such a sensor device can be processed and presented to an operator. B-scan images can be produced that reveal depth characteristics of an inspected structure. C-scan images can be produced to reveal a mapping of the inspected structure. These images can reveal features that are not easily perceived or characterized by simple visual inspection of the exterior of a structure. Collecting data for B-scan and C-scan images typically entails moving a sensor along a portion of a structure in order to collect data across an area of the inspected structure.
Two-dimensional arrays of ultrasonic pulse-echo sensors have been developed and employed in NDI procedures. Such arrays provide numerous sensors regularly distributed across an area and each sensor can collect location-specific data. Thus, a mapping of a portion of the interior structure of a manufactured article can be obtained without movement of the sensors.
When inspecting a structure, a display is typically needed in order to view images of the structure being inspected. For example, on-site inspection may require a computer or laptop having a screen for viewing displayed images and processing data associated with the displayed images. However, the image display information must be accurately transferred to registered locations in the structure.
It would therefore be advantageous to provide an ultrasonic inspection system that is capable of accurately transferring a displayed image onto a structure. In addition, it would be advantageous to provide an ultrasonic inspection system that is portable, lightweight and capable of inspecting structures effectively and efficiently with the results displayed proximate to the inspection zone. Furthermore, it would be advantageous to provide an ultrasonic inspection system that is economical to manufacture and use. In addition, it would be advantageous to provide simple methods for ultrasonic inspection of a structure by disposition of a flexible sensor array overlying a damage site on the structure with minimal physical interaction with the array during set-up and without further movement of the array during data acquisition. In addition, it would be advantageous to provide simple one-sided ultrasonic inspection methods for detecting and characterizing damage beneath contoured surfaces of structures in cases where access to the damage site is limited.